When a person communicates over a telephone network while located in a noisy environment, such as a noisy room, an airport, a car, a street comer or a restaurant, it can often be difficult to hear the person speaking at the other end (i.e., the "far-end") of the connection over the background noise present at the listener's location (i.e., the "near-end" or the "destination"). In some cases, due to the variability of human speech, the far-end speaker's voice is sometimes intelligible over the near-end background noise and sometimes unintelligible. Moreover, the noise level at the near-end may itself vary over time, making the far-end speaker's voice level at times adequate and at times inadequate.
Although terminal telephone equipment sometimes provides for control of the volume level of the telephone loudspeaker (i.e., the earpiece), such control is often unavailable. Moreover, manual adjustment of a volume control by the listener is undesirable since, as the background noise level changes, the user will want to readjust the manual volume control in an attempt to maintain a preferred listening level. Generally, it is likely to be considered more desirable to provide an automatic (i.e., adaptive) control mechanism, rather than requiring the listener first to determine the existence of the problem and then to take action by adjusting a manual volume control. One solution which attempts to address this problem has been proposed in U.S. Pat. No. 4,829,565, issued on May 9, 1989 to Robert M. Goldberg, which discloses a telephone with an automated volume control whose gain is a function of the level of the background noise.